diff --git a/common/flatpak-run.c b/common/flatpak-run.c
index f510a94a..5e49f092 100644
--- a/common/flatpak-run.c
+++ b/common/flatpak-run.c
@@ -2171,6 +2171,8 @@ flatpak_run_add_extension_args (GPtrArray    *argv_array,
   g_auto(GStrv) parts = NULL;
   gboolean is_app;
   GList *extensions, *l;
+  g_autoptr(GHashTable) mounted_tmpfs =
+    g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
 
   parts = g_strsplit (full_ref, "/", 0);
   if (g_strv_length (parts) != 4)
@@ -2191,9 +2193,13 @@ flatpak_run_add_extension_args (GPtrArray    *argv_array,
       if (ext->needs_tmpfs)
         {
           g_autofree char *parent = g_path_get_dirname (full_directory);
-          add_args (argv_array,
-                    "--tmpfs", parent,
-                    NULL);
+          if (g_hash_table_lookup (mounted_tmpfs, parent) == NULL)
+            {
+              add_args (argv_array,
+                        "--tmpfs", parent,
+                        NULL);
+              g_hash_table_insert (mounted_tmpfs, g_steal_pointer (&parent), "mounted");
+            }
         }
 
       add_args (argv_array,
diff --git a/common/flatpak-utils.c b/common/flatpak-utils.c
index d48feddb..30ac34d0 100644
--- a/common/flatpak-utils.c
+++ b/common/flatpak-utils.c
@@ -3532,7 +3532,6 @@ flatpak_list_extensions (GKeyFile   *metakey,
               g_auto(GStrv) refs = NULL;
               g_auto(GStrv) unmaintained_refs = NULL;
               int j;
-              gboolean needs_tmpfs = TRUE;
 
               refs = flatpak_list_deployed_refs ("runtime", prefix, arch, branch,
                                                  NULL, NULL);
@@ -3545,8 +3544,7 @@ flatpak_list_extensions (GKeyFile   *metakey,
                   if (subdir_files)
                     {
                       ext = flatpak_extension_new (extension, refs[j], dir_ref, extended_dir, subdir_files, FALSE);
-                      ext->needs_tmpfs = needs_tmpfs;
-                      needs_tmpfs = FALSE; /* Only first subdir needs a tmpfs */
+                      ext->needs_tmpfs = TRUE;
                       res = g_list_prepend (res, ext);
                     }
                 }
@@ -3562,8 +3560,7 @@ flatpak_list_extensions (GKeyFile   *metakey,
                   if (subdir_files)
                     {
                       ext = flatpak_extension_new (extension, unmaintained_refs[j], dir_ref, extended_dir, subdir_files, TRUE);
-                      ext->needs_tmpfs = needs_tmpfs;
-                      needs_tmpfs = FALSE; /* Only first subdir needs a tmpfs */
+                      ext->needs_tmpfs = TRUE;
                       res = g_list_prepend (res, ext);
                     }
                 }